In existing D4 digital channel banks which include DS1 Super Frame (SF), DS1 Extended Super Frame (ESF) and unrestricted use of dataport type channel units including 64 kilobit clear channel capability, a problem exists regarding the emulation of an inband yellow alarm condition. As is known, in the DS1 SF format, yellow alarm information is transmitted inband by inserting logical 0's in bit position two (2) of each time slot in a frame. In the existing D4 channel bank transcoding process, the D4 DS1 Super Frames, including any inband yellow alarm bits or data patterns emulating a yellow alarm condition, are supplied, i.e., passed through, to a DS1 SF/ESF framer for transmission in the ESF format. In existing D4 channel bank receivers, received DS1 ESF frames including any inband yellow alarm bits, or data bits emulating a yellow alarm condition are passed through to frames in the D4 DS1 SF format. Consequently, any data being transmitted, for example, in a clear channel mode, could be corrupted by the inband yellow alarm transmission process. Additionally, any received data emulating a yellow alarm condition will cause the receiving channel bank to declare a "false" yellow alarm condition. Both of these situations are undesirable. Thus, although existing D4 channel banks including DS1 ESF format capability operate satisfactorily in most applications, they would operate unsatisfactorily in applications involving the unrestricted use of dataport type channel units including 64 kilobit clear channel capability.